There are about six million young people (15-24 years) with HIV globally. Young women age 15 to 24 years who engage in high risk (YWHR) sexual activity are one of the most-at-risk populations in Uganda; HIV prevalence among this group has been estimated at 26% compared to national prevalence of 4.9%, and Uganda's total fertility rate continues to rank among the highest in the world. Young HIV-uninfected women are especially vulnerable to sexually transmitted infections (STI) including HIV and unplanned pregnancies and thus are in particular need of effective HIV prevention, care, support, and reproductive health services. Young Ugandan women who engage in transactional sex work, are particularly vulnerable. This study aims to develop and test a structural and cognitive behavioral prevention intervention package for HIV-uninfected young women aged 15-24 engaging in high risk sexual behavior in Kampala, Uganda. The prevention intervention will use a three-prong approach for these high-risk women consisting in: 1) peer group sessions that include alternative livelihood options and mentoring, 2) networking and healthy behavior reinforcement through mobile technology, and 3) cognitive behavioral counselling by a trusted adult. We will conduct a stratified randomized controlled trial among a total of 450 HIV-uninfected high risk women 15-24 years old followed for 18 months in an existing specialized community-based clinic in Kampala, Uganda providing services to 2300 female sex workers aged 15 and older. The specific aims of the study will be: 1) To conduct formative research exploring the dynamics of the social and sexual networks, mobility and context of young women (aged 15-24) in Kampala, Uganda; 2) To assess the effectiveness of a combination prevention intervention on the frequency of unprotected sex and 3) To assess the effect of combination prevention intervention on reducing the unmet need for family planning (FP) and the incidence of unintended pregnancies. Women will be consented, enrolled and randomized to receive either the intervention including 4 interactive group sessions and two one-on-one counselling sessions or standard prevention services for HIV and other STI guided by Ministry of Health trained counsellors including condom distribution. Participants will be followed for 18 months. This study will be an important first step towards informing national policy and guidelines about the effect of a structural/cognitive behavioral, youth-friendly approach to HIV care and treatment for young high risk women in Uganda.